I've added a new BBCode for Youtube tonight. It works like this (removing extra spaces and filling in the blank):
[ youtube ] ______ [/ youtube ]
Fill in the blank with the "V" value from a normal Youtube URL. For example: https://www.youtube.com/watch?v=OcfQVmEGGS0
would be shared as:
[ youtube ]OcfQVmEGGS0[/ youtube ]
Then you can center it by enclosing it in some [ align=center ]... [/ align] tags. Like this...